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Re: pg_plan_advice

Alexander Lakhin <exclusion@gmail.com>

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From: Alexander Lakhin <exclusion@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>, Melanie Plageman <melanieplageman@gmail.com>
Cc: Nathan Bossart <nathandbossart@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, Lukas Fittl <lukas@fittl.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, "heikki.linnakangas" <heikki.linnakangas@iki.fi>
Date: 2026-04-14T18:00:01Z
Lists: pgsql-hackers 
13.04.2026 19:01, Robert Haas wrote:
> Sounds like we have a consensus. I have committed the three bug-fix
> patches (unrelated to the retry-loop stuff) ...

Thanks again for committing these fixes, Robert! With all the fixes in
place, I and SQLsmith have reached another error:
CREATE TABLE t1(a int);
CREATE TABLE t2(b int);

SELECT 1 FROM t1 WHERE EXISTS
   (SELECT 1 FROM
     (SELECT 1 FROM
       (SELECT 1) LEFT JOIN t2 ON true),
     t2 WHERE a = b);

ERROR:  XX000: unique semijoin found for relids (b 3 5 7) but not observed during planning
LOCATION:  pgpa_plan_walker, pgpa_walker.c:153

Could you please have a look?

Best regards,
Alexander

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. pg_plan_advice: Fix another unique-semijoin bug.

  2. pg_plan_advice: Export feedback-related definitions.

  3. pg_plan_advice: Fix a bug when a subquery is pruned away entirely.

  4. pg_plan_advice: Add alternatives test to Makefile.

  5. pg_plan_advice: Handle non-repeatable TABLESAMPLE scans.

  6. pg_stash_advice: Allow stashed advice to be persisted to disk.

  7. Add pg_stash_advice contrib module.

  8. pg_plan_advice: Avoid assertion failure with partitionwise aggregate.

  9. pg_plan_advice: Invent DO_NOT_SCAN(relation_identifier).

  10. Add an alternative_plan_name field to PlannerInfo.

  11. pg_plan_advice: Refactor to invent pgpa_planner_info

  12. Respect disabled_nodes in fix_alternative_subplan.

  13. get_memoize_path: Don't exit quickly when PGS_NESTLOOP_PLAIN is unset.

  14. test_plan_advice: Set TAP test priority 50 in meson.build.

  15. pg_plan_advice: Avoid a crash under GEQO.

  16. Test pg_plan_advice using a new test_plan_advice module.

  17. pg_plan_advice: Always install pg_plan_advice.h, and in the right place

  18. pg_plan_advice: Fix failures to accept identifier keywords.

  19. Add pg_plan_advice contrib module.

  20. Allow extensions to mark an individual index as disabled.

  21. Replace get_relation_info_hook with build_simple_rel_hook.

  22. Store information about Append node consolidation in the final plan.

  23. Store information about elided nodes in the final plan.

  24. Store information about range-table flattening in the final plan.

  25. Pass cursorOptions to planner_setup_hook.

  26. Fix PGS_CONSIDER_NONPARTIAL interaction with Materialize nodes.

  27. Fix mistakes in commit 4020b370f214315b8c10430301898ac21658143f

  28. Allow for plugin control over path generation strategies.

  29. Update some comments for fasthash

  30. Allow passing a pointer to GetNamedDSMSegment()'s init callback.

  31. Don't reset the pathlist of partitioned joinrels.

  32. Treat number of disabled nodes in a path as a separate cost metric.